The present invention relates generally to the field of electronic devices with touch-sensitive surfaces, and more particularly to controlling the interactions and selections associated with multiple users accessing a single electronic device with touch-sensitive surfaces.
Touch-sensitive surfaces (also known as touchscreens) are becoming commonplace in everything from mobile computing devices (e.g., personal computers, tablet computers, smartphones, etc.) to large display touchscreen interfaces (e.g., touch walls). Touchscreens are electronic visual displays that allow a user to control and manipulate computer programs by touching the screen with a special stylus and/or a finger. The development of multi-touch interaction techniques (i.e., the ability of a touch-sensitive surface to recognize the presence of more than one or more than two different points of contact with the touch-sensitive surface) furthers the capabilities of touchscreens. Multi-touch enabled touchscreens allow the utilization of more complex gestures (e.g., pinch, zoom, etc.) and for multiple users to interact with the touchscreen simultaneously.
Multi-touch interaction techniques can be implemented in several different ways, depending on the size and type of interface. Two common multi-touch techniques are capacitive and optical. Capacitive touchscreens (e.g., smart phones, tablet computers, etc.) monitor changes in electrical currents running through the touchscreen through a layer of capacitive or electricity-storing material in which the capacitors are arranged according to a coordinate system that creates a coordinate grid. Optical touchscreens (e.g., touch wall, touch tables, etc.) project an image through acrylic or glass and then back-light the image with light emitting diodes (LEDs) also creating a coordinate grid but utilize sensors and cameras to capture the scattering of light and reflections. In both techniques, when contact with the touchscreen occurs, a disruption is registered within the coordinate grid along with the gesture, which is then sent to the software and processed. As every individual point of the coordinate grid generates a signal when touched, capacitive and optical touchscreen devices are capable of recognizing multiple points of contact and multiple users.
The grid in a two-dimensional system, such as in the touchscreen, is a Cartesian coordinate system (e.g., rectangular coordinate system, x-y coordinate system). The Cartesian coordinate system specifies each point uniquely in a plane by a pair of numerical coordinates referred to as an ordered pair. The ordered pair is a signed distance, measured in the same unit length, from the origin point which is identified by the intersection of two fixed perpendicular reference lines known as the x-axis and y-axis. By applying the Cartesian coordinate system to the touchscreen, a unique (x, y) coordinate value is associated with each point of the surface, thus allowing the determination of a location corresponding to the perceived interaction. The locations are also associated with the known location of the displayed application software. By combining the location and interpreting the gestures, appropriate responses are displayed.